I am currently doing a design project on Cirrus SR 20, mainly performing analysis for this aircraft and then comparing the results what I have calculated with the real values. I initially started with takeoff weight estimations and selected the mission profile. I had doubts in the fuel consumption:
The estimated fuel for engine start, taxi and takeoff is 1.0 gallons (6 lbs). Therefore, after fuel consumption during warm up and takeoff the weight reduces to 6 lbs less that is 2994 lbs. The weight fraction for takeoff and warm up is 0.998
For climb (1-2) the amount of fuel consumed is 2.4 gallons (14.4 lbs). Therefore, after the fuel consumption during climb segment the weight reduces to 14.4 lbs less that is 2979.6 lbs. The weight fraction for climb is 0.995
For cruise (2-3) the amount of fuel consumed is 41.4 gallons (248.4 lbs). Therefore, after fuel consumption during the cruise segment the weight reduces to 248.4 lbs less that is 2731.2 lbs. The weight fraction for cruise is 0.916
For Loiter (3-4) the amount of reserve fuel for 45 minutes is 8.3 gallons (49.8 lbs). Therefore, after fuel consumption during loiter the weight reduces to 49.8 lbs less that is 2681.4 lbs. The weight fraction for loiter is 0.918
For landing (4-5) the amount fuel required is unknown to me. Since in the manual the usable fuel is 56 gallons. Till now what I have calculated above shown is 53.1 gallons, therefore remaining fuel is 2.9 gallons which is not possible for landing.
Can someone guide me please. It would be great help.